Hydraulic turbines for borehole drilling



F. WHITTLE Jan. 23, 1968 HYDRAULIC TURBINES FOR BOREHOLE DRILLING 2 Sheets-5neet 1 Filed Sept. 14, 1965 Jan. 23, 1968 F. WHITTLE HYDRAULIC TURBINES FOR BOREHOLE DRILLING 2 SheetsSnee1 2 1 Filed Sept. 14, 1965.

Q Inventor 591M l/fl/zns 4 A Home s United States Patent 3,365,170 HYDRAULIC TURBINES FOR BOREHOLE DRILLING Frank Whittle, Wailand Hill, (lhagford, Devonshire, England Filed Sept. 14, 1965, Ser. No. 487,269 Claims priority, application Great Britain, Sept. 16, 1964, 37,871/64 (Ilairns. (Cl. 253-3) ABSTRACT OF THE DISCLOSURE A turbo-drill having inner and outer contra-rotating turbines, a reduction gear connecting these turbines together and to a drill bit, and oil lubricated thrust bearings, has the turbines located below the thrust bearings so that removal and replacement of the turbine blades is facilitated and so that a common supply of oil can be provided to both the thrust bearings and the reduction gear.

United States Patent No. 2,937,008 describes a hydraulic turbine unit for borehole drilling in which there are two contra-rotating blade-carrying rotors, one of which is arranged for connection directly or indirectly to a drill bit; the rotors being geared to a tubular member which is arranged for connection, directly or through a hydraulic loading ram, to the bottom end of a hollow drill string, to receive therefrom a supply of fluid for operating the turbine and to transmit thereto the torque reaction from the bit.

In the construction described in Patent No. 2,937,008 the tubular member is in the form of a casing which surrounds and substantially encloses the blade-carrying rotors, while a main thrust bearing assembly for the outer rotor, which has an output shaft for connection to the drill bit, is arranged between the blade-carrying part of that rotor and the casing, the gearing being arranged above the rotors. In a later design, the main thrust bearing assembly is arranged below the blade-carrying part of the outer rotor. This permits a somewhat larger diameter turbine to be used, but with both arrangements separate lubrication systems are necessary for the main thrust bearing assembly and the gearing, since it is not practical to interconnect them. Furthermore a clearance space exists between the outer rotor and the casing, and this space, which is closed at its lower end by a seal protecting the main thrust bearing assembly, is liable to become filled with grit from the drilling fluid. Another drawback with this arrangement is that, to permit withdrawal of the turbine and gearbox assemblies from the casing for overhaul, a sliding support has to be used between the casing and the gearbox. Wear has been found to occur in this support which may allow eccentricity of the outer rotor in the casing and increase the difiiculty of sealing the clearance space against entry of grit.

According to the present invention a hydraulic turbine unit for borehole drilling comprises: a tubular member for connection to the bottom end of a hollow drill string to receive therefrom a supply of fluid for operating the turbine; a sleeve having an upper part overlapping the tubular member and mounted for rotation thereon by a thrust bearing, and a lower part extending below the tubular member and carrying a plurality of rows of inweirdly-projecting turbine blades and having a lower end for connection to a drill bit; a shaft journalled for rotation within the lower part of the sleeve and carrying rows of cooperating outwardly-projecting turbine blades; gearing lying above the blades and connecting the tubular member, sleeve, and shaft for rotation relatively to one another; and a lubricant supply connected both to the thrust bearing and to the gearing.

3,365,170 Patented Jan. 23, 1968 The terms upper, lower, above refer to the unit when in operative attitude. The connections to the drill string and to the drill bit may be direct or indirect. In particular, there maybe a ram between the tubular member and the drill string.

The gearing is such that the sleeve and shaft rotate oppositely, relatively to the tubular member, at lower and higher speeds respectively.

It will be appreciated that with this arrangement there is no casing outside the sleeve, which constitutes the outer rotor, so that the turbine can be made larger in diameter than in previous arrangements. This enables the shaft to rotate at a lower speed, while the output to the drill bit provides the same speed and torque as hitherto; in consequence the gearing may be more compact. In addition, the turbine blades, which are subject to severe errosion by the drilling fluid, can be readily removed and replaced.

Furthermore, when the unit is used in conjunction with a hydraulic loading ram connected between the tubular member and the drill string, the hydraulic system of the ram can be integrated with the lubrication system.

The invention is illustrated by the example of a turbine unit and loading ram shown in the accompanying diagrammatic drawings.

The three figures of the drawings, if joined together on the lines AA and B--B, show all the relevant parts of the equipment, proceeding from the top downwards in axial section. More particularly:

FIGURE 1 shows a lower part of the ram and an upper end part of the turbine unit;

FIGURE 2 shows a middle section of the turbine unit comprising mainly the bearings, gearbox, and equipment for operating the ram; and

FIGURE 3 shows the lower end part of the turbine unit, comprising mainly the blade-carrying rotors, and also the coupling part of a drill bit or collar member attached to the output coupling.

The loading ram, of which the lower part is shown in FIGURE 1, comprises a central tubular piston rod 10, through which drilling fluid is supplied to the turbine, carrying an annular piston 11 operating in a cylinder 12 formed within an outer casing 13. Sealing means 14 and 15 are provided where the rod 10 passes through a lower diaphragm 16 and an upper diaphragm 17 respectively. Above the upper diaphragm the rod 10 is provided with torque transmission splines (not shown) engaging corresponding splines carried by the casing 13, so that the torque reaction of the drill bit may be transmitted to the drill string (not shown), which is coupled to the upper end of the casing 13. The ram may if desired be provided with additional pistons operating in further cylinders provided in tandem in the casing. Also, the torque transmission means may if desired be constituted by a series of splined telescopic tubular members housed in one of the cylinder chambers of the ram so as to be lubricated by its working fluid, which is lubricating oil supplied to it by a pump driven by the turbine as presently described in more detail.

The lower end of the piston rod 10 is connected by coupling means, not shown in detail, to a part 18 of the turbine unit. This part 18, and a part 18a fixed to it, together constitute the tubular member referred to earlier in this specification. As seen in FIGURES 2 and 3, the upper part of a sleeve 19 overlaps the part of the tubular member, the lower part of the tubular member lying inside the sleeve. The sleeve is mounted for rotation on the tubular member by an upper bearing assembly constituted by two taper roller bearings 21 and 22, taking radial loads and axial thrust, and by a lower roller bearing 23, which takes radial loads only. This lower bearing 23 is mounted between the part 18a of the tubular member and a spigot piston 19a of the sleeve which extends upwards inside the lower end of the tubular member, being connected to the rest of the sleeve 19 by vanes 54. A part 195 of the sleeve extending below the part 18a of the tubular member carries a plurality of rows of inwardly-projecting turbine blades 24, and is formed below the blades with a coupling screw thread 25 to receive the tubular upper end of a drill bit or connecting collar 26. The drilling fluid passes through the drill bit or collar in the conventional manner. A perforated screen 27 is provided to prevent upward entry of large pieces of rock debris when the drill is being lowered into the borehole.

The turbine blades 24 contra-rotate relatively to cooperating blades 28 projecting outwardly from a shaft 29. The shaft 29 has a part 29a projecting upwards into the spigot portion 19a of the sleeve, and journalled for rotation therein by an upper bearing assembly constituted by two ball bearings 31 and 32, taking radial loads and end thrust, and by a lower roller bearing 33 taking radial loads only.

The rows of turbine blades 24 and 28 are retained in position by ring nuts 93, 94. To enable the blades to be removed and replaced, it is only necessary to uncouple the drill bit at 25, and then remove the ring nuts 93, 94.

The tubular member 18, 18a, the sleeve 19, and the shaft 29 are geared together for rotation relatively to one another by gearing shown towards the lower end of FIGURE 2. This includes a number of planet gears 34 mounted on shafts 35 projecting axially from a planet carrier constituted by the upper end of the spigot portion 19a of the sleeve. These planet gears mesh on the one hand with internal gear teeth 36 on the part 18a of the tubular member and on the other hand with sunwheel teeth 37 on a small-diameter lower part of an annulus 38. A large-diameter upper part of the annulus 38 is provided with internal gear teeth 39, which mesh with a number of planet gears 40 mounted on shafts 41 carried by the part 18a of the tubular member. These planet gears 40 also mesh with a sunwheel gear 42 attached to the part 2911 of the inner turbine rotor shaft 29. The effect of this gearing is to cause the sleeve 19 (constituting the outer rotor of the turbine and the power output shaft) and the shaft 29 (constituting the inner rotor of the turbine) to rotate oppositely, relatively to the tubular member 18, 18a attached to the drill string, at lower and higher speeds respectively. The speed of the inner rotor may conveniently be about six times that of the outer rotor.

The hollow interior of the tubular member 18, 18a constitutes a continuation 56a of the drilling fluid passage 50 of the ram to a point just below the main thrust bearings 21, 22. From this point, passages 51 passing between vanes 52 carry the fluid to the outside of the tubular member, and it then flows through a clearance space 53 between the outside of the part 18a of the tubular member and the inside of the sleeve 19 until the end of the part 18a is reached, the inner surface of the passage then being constituted by the outside of the spigot portion 19a of the sleeve, which, as mentioned above, is connected to the blade carrying part 1% of the sleeve by vanes 54 passing across the passage. After passing between the turbine blade rows 24 and 28, the fluid is discharged through the drill as already mentioned.

Lu'bricating oil is supplied under pressure to the upper working chamber 55 of the ram by a gear pump 56 driven by an extension of the part 29a of the inner rotor shaft. From the pump the oil passes upwards through a central tube 57 to a ram control valve system 58 housed in an island member 59 supported in the drilling fluid passage by vanes 60. The valve system is not shown in detail as it is not relevant to the present invention. The system may however be similar to that shown in FIGURE of U.S. Patent No. 3,203,184. After passing through the valve system, the oil flows upwards through another central tube 61, and enters the upper working chamber 55 of the ram at a position 62 just above the piston 11, which is shown at the upper end of its range of movement in the cylinder 12. As the piston moves downwards to follow up the progress of the drill, oil is discharged from the lower working chamber 63 of the ram through an opening 64 just beiow the piston into the inner space 65 of a double-walled portion of the piston rod 10, the space 65 constituting an annular return flow passage for the oil.

After the connection between the piston rod 10 and the upper end of the tubular member 18 of the turbine unit, the annular return flow passage 65 is continued into the member 18 and connects with the upper part of an enlargement which is divided into outer and inner annuli 70a and 7% respectively by a flexible sleeve 71, the upper and lower ends of which are clamped to the wall of the enlargement in an oil-tight manner. The outer annulus 70a constitutes an oil reservoir containing a reserve of oil to compensate for leakage, and the inner annulus 70b is connected to the drilling fluid passage 50a by openings 72 in the inner wall of the enlargement so that the oil in the reservoir 70a is maintained at a pressure approximately equal to that in the adjacent passage 59a.

From the reservoir 70a the oil passes through passages 73 into an annular collection groove 74 which is con: nected 0n the one hand by a passage 75 to a chamber 76 containing the main thrust bearings 21, 22 and closed at its ends by sealing devices 77 and 78, and on the other hand by a passage 79 to the control valve system 58. From the control valve system the return flow oil passes, through the annular space between the oil supply tube 57 and a tube 80 which concentrically surrounds it, to a chamber 81 containing the pump 56, and from the chamber 81 through a passage 82 into a filter chamber 83. After passing through the filter element, the oil returns to the pump inlet by way of a chamber 84 surrounding the pump driving shaft and a passage 85. A passage 86 from the filter chamber allows replenishment oil to enter the chamber 87 containing the gearing, the lower bearing 23 of the outer rotor sleeve 19, and the bearings 31, 32 and 33 of the inner rotor shaft 29, this chamber being closed at its upper and lower ends by seals 88, and 89, respectively. Replenishment oil may be supplied to the system through a nipple 91 connected to the main thrust bearing chamber 76 by a passage 92. The system is preferably also provided with screw plugs (not shown) at suitable positions to allow any trapped air to be bled off.

Attention is directed to the fact that the pressure drop across each of the oil seals 78, 83, 89 and 90 is not very large, since the oil is substantially at the pressure of the drilling fluid immediately upstream of the island 59 and the fall in pressure of the drilling fluid between that position and its point of entry into the turbine blades is not very great. On the other hand, the seal 77 separates the lubrication system from the fluid in the borehole outside the drill, so that the whole of the pressure drop in the turbine, in the drill bit and in that part of the borehole which is below the level of the seal 77 is elfective across the seal. For this reason it is necessary to use a very effective and reliable sealing device in this position. The construction of the seal 77 does not form part of the pres ent invention, but U.S. Patent Appl. No. 935,290 relates to a form of seal which is suitable.

It will be seen that the lubricant supply, constituted by the pump 56 and reservoir 70a, is connected both to the thrust bearing 21, 22 and to the gearing, and also to the ram. Furthermore, the lubricant supply is connected in parallel to the thrust bearing and to the gearbox. This ensures that if any damage should occur to the seal 77 and to the thrust bearing 21, 22 fragments of solid material will not be carried to the gearing, nor yet to the ram and its control valve system 58.

It will also be seen that the thrust bearing 21, 22 lies above the gearing and pump, but below the reservoir, so that there is space for it to be of large diameter and robust construction. Furthermore, the part 18a which carries the bearing 21, 22 is of robust and rigid construction so that the sleeve is supported as truly as possible.

The arrangement of the spigot portion 19a of the sleeve enables the bearings 31 and 23 to lie in positions readily connected to the lubricant supply.

It should be noted that the construction as shown in FIGURE 2 is diagrammatic; in practice the part 119a and the sleeve 19 would each need to be made of several pieces fixed together, to permit assembly of the other components.

FIGURE 4 of the accompanying drawings is a fragmentary view similar to FIGURE 2, but showing more details of construction.

The part 18a of the tubular member has separate lower terminal pieces 18x, 18y. The piece 18x is secured by studs and nuts 95. The piece 18y is secured by a ring nut 96. The sleeve 19 has an upper internal piece 19x, secured by a ring nut 97. Associated with the nut 97 is a static oil seal 98.

I claim:

1. A hydraulic turbine unit for borehole drilling comprising a tubular part adapted for connection to the bottom end of a hollow drill string through which a supply of fluid for operating the turbine is fed; a sleeve having a lower end, a plurality of rows of inwardly-projecting turbine blades carried on the lower end, said lower end adapted for connection to a drill bit; a thrust bearing supporting said sleeve for rotation on the outside of said tubular part; a shaft having a lower end, rows of outwardly-projecting turbine blades carried on the lower end of the shaft and cooperating with the first mentioned turbine blades, the shaft journalled for rotation within said sleeve; gearing, arranged above said turbine blades, operative to connect said tubular part, said sleeve, and said shaft for relative rotation with respect to one another; the lower end of said sleeve and the lower end of said shaft extending below said tubular part, the inwardlyprojecting turbine blades and the outwardl rojecting turbine blades lying below said thrust bearing.

2. A hydraulic turbine unit according to claim 1, having a lubricant supply and means connecting said supply both to said gearing and to said thrust bearing.

3. A turbine unit according to claim 1, in which the thrust bearing lies above the gearing, and there is a radial bearing lying between the tubular member and the sleeve and below the gearing but above the blades.

4. A turbine unit according to claim 3, in which the radial bearing lies between the tubular member and a spigot portion of the sleeve which extends upwards inside the tubular member.

5. A turbine unit according to claim 4, in which the fluid flows through ports in the tubular member below the thrust hearing, so as to reach an annular space between the tubular member and the upper part of the sleeve, and then flows through ports in the spigot portion of the sleeve below the radial bearing so as to reach the interior of the sleeve.

6. A turbine unit according to claim 1, in which all the bearings between the tubular member and the sleeve are connected to the lubricant supply.

7. A turbine unit according to claim 3, in which the lubricant supply is connected in parallel to the thrust bearing and to the gearbox.

8. A turbine unit according to claim 1, including a lubricant reservoir Within the tubular member above the thrust bearing, and a lubricant pump below the thrust bearing.

9. A turbine unit according to claim 1, in which the reservoir includes a flexible wall portion which is subjected on its side remote from the lubricant to the pressure of the turbine drilling fluid upstream of the turbine.

10. A turbine unit according to claim 1, in combination with a ram arranged to exert downward thrust on the tubular member, and connected to be actuated by pressure from the lubricant supply.

References Cited UNITED STATES PATENTS 2,800,296 7/1957 Hatch et al. -l07 X 2,937,008 5/1960 Whittle 2533 FOREIGN PATENTS 368,957 3/1932 Great Britain. 814,957 6/1959 Great Britain.

EVERETTE A. POWELL, 111., Primary Examiner, 

